U.S. Pat. No. 5,376,410 to the present applicant disclose a process for modifying the surface of a material to which the present invention pertains. Canadian patent # 1,337,622 also to the present applicant discloses a generic tool to effect the process. U.S. Pat. No. 6,553,869 also by the present applicant discloses a method of fabricating toothed blades for such a tool. The present invention discloses an improvement to this tool with structures offering ease of manufacture, assembly and use.